Abstract:Objective To investigate changes to the expression of reduced nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) and signal transducer and activator of transcription 3 (STAT3) during the activation and proliferation of hepatic stellate cells and to explore whether the NOX4 inhibitor GKT137831 can reduce the production of reactive oxygen species (ROS), as well as inhibit the STAT3 signaling pathway and the activation and proliferation of hepatic stellate cells. Methods Rat hepatic stellate cells-T6 (HSCs-T6) were divided into four groups: control group, TGF-β1 group, TGF-β1+GKT137831 group, and GKT137831 group. The ROS levels in HSC-T6 cells were detected by DCFH-DA fluorescent probe method . The CCK-8 method was used to detect cell proliferation, and real-time fluorescent quantitative PCR was used to detect the expression of NOX4 and STAT3 mRNA. The expression of NOX4, STAT3, p-STAT3, and α-SMA proteins was detected by immunofluorescence and Western blot. Results Compared with the control group, HSC-T6 cells in the TGF-β1 group’s expression of NOX4 mRNA and protein were up-regulated, and intracellular ROS levels, expression of p-STAT3 protein, and the cells’ activation and proliferation ability increased (P< 0. 05). After addition of GKT137831, NOX4 mRNA and protein expressions were down-regulated in HSC-T6 cells, and intracellular ROS levels, STAT3 protein phosphorylation, and the cells’ activation and proliferation ability were decreased (P<0. 05). Conclusions NOX4 may promote the phosphorylation of STAT3 by producing ROS, leading to the activation and proliferation of HSC-T6 cells. By inhibiting NOX4, GKT137831 reduces ROS production and inhibits STAT3 phosphorylation, thereby inhibiting HSC-T6 cell activation and proliferation.